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Cotton-Candy-Like Injectable Brings Bleeding to a Halt

illustration of vein rupture bleeding after cut

If you’ve ever watched a crime procedural, you know that you put pressure on anything that’s bleeding. But what if the bleeding is internal? Procedures like a transfusion of clotting factors can help, but that can’t happen in the field. Now, a new material might be coming to the rescue.

Often, when internal bleeding is detected, doctors will order a transfusion of platelets, the repairmen in our bloodstreams. But even if first responders could do transfusions, the problem is that storing such materials requires refrigeration and care that isn’t practical. 

The Golden Hour

“A lot of trauma-related deaths happen within the first hour when blood loss is happening profusely, and there is no intervention,” said Yongsheng Gao, a postdoctoral research associate at Harvard’s John A Paulson School of Engineering and Applied Sciences (SEAS). “A key objective for first responders is to keep trauma patients alive during this so-called golden hour and in that time bring them to a hospital because once they get to the hospital, it’s a different game altogether.”

Enter HAPPI, which stands for Hemostatic Agents via Polymer Peptide Interfusion (so we’ll just go with HAPPI). The material was invented by researchers from SEAS, in collaboration with Massachusetts General Hospital, Beth Israel Deaconess Medical Center, and Case Western Reserve University. The finding has been described in the journal Science Advances.

HAPPI is freeze-dried and has the consistency of cotton candy, and, best of all, it can be stored in a syringe at room temperature for months. 


“Our goal was to give first responders a tool to stop internal bleeding that could be easily carried in a backpack or stored in an ambulance and, once injected intravenously in hemorrhagic patients, stop internal bleeding for a period long enough to get the patient to a hospital,” said Samir Mitragotri, Hiller Professor of Bioengineering and senior author of the study.

The material works by finding its way to the source of the internal bleeding and then lassoing in platelets to help stop the leak. In tests with mice, HAPPI injections led to a 99% reduction in bleeding time and a 97% reduction in the overall loss of blood.

“With HAPPI, we sought to develop a safe and effective internal bandage,” said Apoorva Sarode, a former graduate student at SEAS and the co-first author of the study. “We think that the simple design and scalable synthesis process of HAPPI will facilitate its seamless scale-up and translation to larger animal models, and eventually to the patients.”